Here on Earth, the common notion is that a lake is a body of water surrounded entirely by land. But imagine a lake on Saturn's largest moon, the Titan. The planet itself being so far away from the Sun, it comes as no surprise that the temperature there would be much lower. On Titan, it is 90 degrees Kelvin, in fact.

Surely, this has an effect on the kind of elements present there. If you are to think that nothing else but a body of water can be a lake, then you are highly mistaken. Because on Titan, over 75 lakes ranging in size from about a mile and a half to 40 miles across have been detected, and they are not filled with water. Instead, cradled in the lakes as liquid is methane. Here on Earth, it is a form of gas. But out there, it's clearly liquid.

Dr. Ellen Stofan of the Proxemy Research in Washington DC, as well as a member of the Cassini Radar team explains this as being caused by the really low temperature on the moon. They also believe that the lakes have another kind of hydrocarbon compound of some sorts in them, called ethane.

Interestingly enough, although the chemistry is apparently different on Titan, the lakes' behaviour do resemble their Earthly counterparts. Says Stofan, "The methane-ethane would become transparent, the way water is on Earth, it would be behaving like water, the lakes could have small waves on the surfaces." What also got them into thinking that these are, in fact, lakes is the way that other channels feed into then, their shapes, shorelines, and all of those geological aspects of the lake.

The team's discovery is featured in this week's journal "Nature".